﻿using System.Collections;
using System.Globalization;
using Prism.Ioc;
using Prism.Properties;

namespace Prism.Regions.Behaviors;

/// <summary>
/// Defines a factory that allows the registration of the default set of <see cref="IRegionBehavior"/>, that will
/// be added to the <see cref="IRegionBehaviorCollection"/> of all <see cref="IRegion"/>s, unless overridden on a 'per-region' basis.
/// </summary>
public class RegionBehaviorFactory : IRegionBehaviorFactory
{
    private readonly IContainerProvider _container;
    private readonly Dictionary<string, Type> _registeredBehaviors = new Dictionary<string, Type>();

    /// <summary>
    /// Initializes a new instance of <see cref="RegionBehaviorFactory"/>.
    /// </summary>
    /// <param name="container"><see cref="IContainerExtension"/> used to create the instance of the behavior from its <see cref="Type"/>.</param>
    public RegionBehaviorFactory(IContainerExtension container)
    {
        _container = container;
    }

    /// <summary>
    /// Adds a particular type of RegionBehavior if it was not already registered. The <paramref name="behaviorKey"/> string is used to check if the behavior is already present
    /// </summary>
    /// <typeparam name="TBehavior">Type of the behavior to add.</typeparam>
    /// <param name="behaviorKey">The behavior key that's used to find if a certain behavior is already added.</param>
    public void AddIfMissing<TBehavior>(string behaviorKey)
        where TBehavior : IRegionBehavior
    {
        if (behaviorKey == null)
        {
            throw new ArgumentNullException(nameof(behaviorKey));
        }

        var behaviorType = typeof(TBehavior);

        // Only add the behaviorKey if it doesn't already exists.
        if (_registeredBehaviors.ContainsKey(behaviorKey))
        {
            return;
        }

        _registeredBehaviors.Add(behaviorKey, behaviorType);
    }

    /// <summary>
    /// Creates an instance of the behavior <see cref="Type"/> that is registered using the specified key.
    /// </summary>
    /// <param name="key">The key that is used to register a behavior type.</param>
    /// <returns>A new instance of the behavior. </returns>
    public IRegionBehavior CreateFromKey(string key)
    {
        if (!ContainsKey(key))
        {
            throw new ArgumentException(
                string.Format(CultureInfo.CurrentUICulture, Resources.TypeWithKeyNotRegistered, key), nameof(key));
        }

        return (IRegionBehavior)_container.Resolve(_registeredBehaviors[key]);
    }


    /// <summary>
    /// Returns an enumerator that iterates through the collection.
    /// </summary>
    /// <returns>
    /// A <see cref="T:System.Collections.Generic.IEnumerator`1" /> that can be used to iterate through the collection.
    /// </returns>
    /// <filterpriority>1</filterpriority>
    public IEnumerator<string> GetEnumerator() =>
        _registeredBehaviors.Keys.GetEnumerator();

    /// <summary>
    /// Returns an enumerator that iterates through a collection.
    /// </summary>
    /// <returns>
    /// An <see cref="T:System.Collections.IEnumerator" /> object that can be used to iterate through the collection.
    /// </returns>
    /// <filterpriority>2</filterpriority>
    IEnumerator IEnumerable.GetEnumerator() =>
        GetEnumerator();

    /// <summary>
    /// Determines whether a behavior with the specified key already exists.
    /// </summary>
    /// <param name="behaviorKey">The behavior key.</param>
    /// <returns>
    /// <see langword="true"/> if a behavior with the specified key is present; otherwise, <see langword="false"/>.
    /// </returns>
    public bool ContainsKey(string behaviorKey) =>
        _registeredBehaviors.ContainsKey(behaviorKey);
}
